package com.first.leetcode.LinkedList;

import com.datastructures.ListNode;

/**
 * Merge two sorted linked lists and return it as a new sorted list. The new list should be made by splicing together the nodes of the first two lists.
 *
 * Example:
 *
 * Input: 1->2->4, 1->3->4
 * Output: 1->1->2->3->4->4
 */
public class MergeTwoSortedLists {
    public ListNode mergeTwoLists(ListNode l1, ListNode l2) {
        if (l1 == null && l2 == null) {
            return null;
        }
        if (l1 == null) {
            return l2;
        }
        if (l2 == null) {
            return l1;
        }
        ListNode result = new ListNode(0);
        ListNode prev = result;
        while (l1 != null && l2 != null) {
            if (l1.val <= l2.val) {
                prev.next = l1;
                l1 = l1.next;
            } else {
                prev.next = l2;
                l2 = l2.next;
            }
            prev = prev.next;
        }
        if (l1 != null) {
            prev.next = l1;
        }
        if (l2 != null) {
            prev.next = l2;
        }
        return result.next;
    }

    public ListNode mergeTwoLists2(ListNode l1, ListNode l2) {
        if(l1 == null) return l2;
        if(l2 == null) return l1;
        if(l1.val < l2.val){
            l1.next = mergeTwoLists(l1.next, l2);
            return l1;
        } else{
            l2.next = mergeTwoLists(l1, l2.next);
            return l2;
        }
    }

    public static void main(String[] args) {
        ListNode node1 = new ListNode(1);
        ListNode node2 = new ListNode(2);
        ListNode node3 = new ListNode(4);
        ListNode node4 = new ListNode(1);
        ListNode node5 = new ListNode(3);
        ListNode node6 = new ListNode(4);
        node1.next = node2;
        node2.next = node3;
        node4.next = node5;
        node5.next = node6;
        MergeTwoSortedLists so = new MergeTwoSortedLists();
        ListNode head = so.mergeTwoLists(node1, node4);
        System.out.println(1212);
    }
}
